A kitchen oil fire is a different effect. They're not hot enough to disassociate water molecules. What happens typically is that the water floats the oil, and the fire, remaining on top of the oil, spreads more rapidly.

Another effect is when the fire (and typically, the cooking vessel) are hot enough to vaporize the water. This rapid vaporization spreads oil droplets rapidly, allowing much more of the oil to burn at once. It can appear explosive, even though it's just rapidly-expanding steam spreading fine oil droplets.